1. Field of the Invention
The present invention relates to a silver halide photographic light-sensitive material and, more particularly, a photographic light-sensitive material having a high sensitivity, a high resistance to pressure, and a good desilvering property.
2. Description of the Related Art
Basic properties required for silver halide emulsions for photography are a high sensitivity, a low fog, and a fine graininess.
As a technique for satisfying the above requirements, the use of tabular silver halide grains including dislocation lines is known in recent years (JP-A-63-220238 ("JP-A" means Unexamined Published Japanese Patent Application)).
It is possible to obtain emulsions having a high sensitivity and a high resistance to pressure by using these tabular grains. However, in a system in which an amount of sensitizing dyes is increased to obtain light absorption as much as possible, a resistance to pressure and a desilvering property are significantly degraded.
Generally, various pressures are applied to a photographic light-sensitive material, coated with silver halide emulsions. For example, a photographic negative film for general purposes is taken up by a patrone, bent when loaded in a camera, or pulled upon winding up of a frame.
On the other hand, a sheet-like film such as a printing light-sensitive material or a direct medical roentgen light-sensitive material is often bent because it is directly handled by human hands.
In addition, all light-sensitive materials are subjected to a high pressure when cut or processed.
When various pressures are applied to a photographic light-sensitive material as described above, silver halide grains are pressurized via gelatin contained as a carrier (binder) for the silver halide grains or via a plastic film employed as a support. It is known that photographic properties of a photographic light-sensitive material are changed when pressure is applied to silver halide grains, as reported in detail in, e.g., K. B. Mather, J. Opt. Soc. Am., 38. 1054 (1948); P. Faelens and P. de Smet. Sci. et. Ind Phot., 25. No. 5. 178 (1954); and P. Faelens. J. Phot. Sci. 2. 105 (1954).
For this reason, a strong demand has arisen for a photographic light-sensitive material which can not be adversely affected in photographic properties even if it is subjected to these various pressures.
One of the conventionally known methods of improving resistance to pressure is to prevent pressure from reaching the silver halide grains, for example by adding a plasticizer such as a polymer or an emulsified product to a silver halide emulsion, or by decreasing the silver halide/gelatin ratio of the emulsion.
For example, British Patents 738,618, 738,637, and 738,639 disclose methods using a heterocyclic compound, alkylphthalate, and alkyl ester, respectively. U.S. Pat. Nos. 2,960,404 and 3,121,060 disclose methods using polyhydric alcohol and carboxyalkylcellulose, respectively. JP-A-49-5017 discloses a method using paraffine and carboxylate, and JP-B-53-28086 ("JP-B" means Examined Published Japanese Patent Application) discloses a method using alkylacrylate and an organic acid.
The method of adding a plasticizer, however, lowers the mechanical strength of the emulsion layers, and this imposes limitations on the use of the method. When the ratio of gelatin is increased, on the other hand, the development speed is decreased. Thus, it is difficult for any of these methods to achieve satisfactory effects.
In addition, the use of naphthoxazolocarbocyanine is described in, e.g., JP-B-61-80237, JP-A-60-108838, JP-A-61-8023, JP-A-63-291057, JP-A-61-32841, JP-A-60-225146, JP-A-60-128433, JP-A-60-128132, JP-A-59-185330, JP-A-59-149346, JP-A-59-116646, JP-A-59-78338, JP-A-63-214745 and JP-B-54-34609.
None of these patents disclose or suggest, however, that the effect of the present invention, which is described later, is achieved by a combination of naphthoxazolocarbocyanine represented by Formula (A), (B), or (C) shown hereinafter, an emulsion of a tabular silver halide having dislocations and a polymer compound having a repeating unit represented by Formula (I) or (II) shown hereinafter.